1. Field of the Invention
This invention relates to means and methods of employing a saturable absorptive nonlinear medium to provide contrast enhancement in optical images. Such medium are employed in optical bistable devices, such as a nonlinear Fabry-Perot resonator.
2. Prior Art
Optical image processing is typically performed with devices employing liquid crystal light valves or parallel processing of image data by conventional electronic methods. Many circumstances arise however where parallel processing by electronic means is impossible due to the necessity of opto-electrical and electro-optical conversion. Further, even when electronic parallel processing is involved, very complex systems are required for two dimensional optical images when real time processing is desirable. Additionally, devices employing liquid crystal light valves are too slow for real time processing.
It has been proposed to employ bistable optical devices utilizing nonlinear optical media (i.e., materials whose optical properties depend on the intensity of light passing through them) to form two dimensional arrays for optical image processing (see P. W. Smith and W. J. Tomlinson, "Bistable Optical Devices Promise Subpiocosecond Switching", Advanced Technology-Solid State, IEEE Spectrum, June 1981, pages 26-33). Experiments in this regard have been limited to employing hybrid devices (i.e., devices where the optical nonlinearity is not due solely to the intrinsic optical nonlinearity of a material), with liquid crystal light valves being used in one model.